It is well known that loosely ligamented individuals, as well as individuals with certain peculiar anatomic features of certain components of the knee, frequently develop various pathological problems with their knees, particularly when these individuals are active in physically strenuous activities, such as, for example, athletics. The most commonly occurring problems relate to stretching or tearing of various knee ligaments, injury to the cartilage (meniscal) and articular surfaces of the knee joint, and fractures. Patella subluxation, or abnormal and undesirable movement of the patella, laterally, relative to its normal up-and-down movement in the vertical track defined by the trochlea, can precipitate the onset of chondromalacia or aggravate existing chondromalacia of the patella, as well as cause diagnostic problems and other painful clinical conditions with respect to the knee.
Subluxation of the patella can be caused by certain developmental abnormalities of the skeletal components of the knee and/or the presence of musculoligamentous laxity, or dysplasia. The patella may leave its normal vertical tracking groove as a result of abnormal vector forces and/or by passive lateral or rotary forces. The abrupt abnormal lateral displacement of the patella from its groove during any weight-bearing activity, such as, for example, running, stair climbing, etc., frequently results in an immediate, temporary disability, such as, for example, buckling of the knee, thereby causing a subjective sensation in the knee similar to that caused by other unrelated pathological conditions within the knee.
The sensation of pain and/or imminent buckling of the knee results in apprehension and restriction of certain weight-bearing activities, such as, for example, athletic endeavors. The resultant increased abnormal traction forces on the peripatellar soft tissues frequently lead to inflammatory changes and stretching of the retinaculae, patella ligament and/or tendon (tendinitis).
Furthermore, the repetitive, abnormal lateral excursions, which cause abnormal shearing forces, frequently lead to early, accelerated and progressive degenerative changes (chondromalacia) of the patella and femoral condyles.
As noted above, problems peculiar to the patella comprise only a portion of all common physiological problems of the knee, and several, unrelated or partially related problems may occur simultaneously, particularly in individuals having loose ligaments, or when engaged in relatively strenuous activities involving the knee.
Young children still in the active bone-growth phase of life frequently are relatively loosely ligamented and suffer from various degrees of patella subluxation. It is well recognized that it is preferable to avoid or delay corrective surgery for such individuals, if at all possible, until such individuals reach a more physiologically opportune age, i.e., when their growth plates have closed.
Others have devoted attention and proposed various knee braces and supports directed to general problems of the knee. Examples of such patents are U.S. Pat. No. 3,473,527 to Spiro; U.S. Pat. No. 3,804,084 to Lehman; U.S. Pat. No. 3,853,123 to Moore; and U.S. Pat. No. 4,532,921 to von Torklus et al., which have proposed various knee-support, brace and knee-splinting devices intended to restrain the knee to prevent normal knee flexion or movement. These are but a few of the patents directed to knee supports.
U.S. Pat. No. 3,926,186 to Nirschl and U.S. Pat. No. 3,945,046 to Stromgern propose other muscular and flexible knee supports. Nirschl's apparatus, however, is not designed to provide medial-lateral stabilization of the patella, and is inherently incapable of performing a dynamic bracing function for the patella. Stromgern's apparatus, on the other hand, is not concerned with patella stabilization, but, instead, is directed to the general problem of providing stability to the medial knee ligament complex.
U.S. Pat. No. 4,084,585 to Detty discloses a simple knee sleeve device which includes a pad but which is capable of providing limited, static patella bracing when the knee is passive, i.e., not in motion or when in a single position or a narrow range of positions.
Perhaps the seminal patent for providing dynamic patella bracing is U.S. Pat. No. 4,296,744 to Palumbo, the inventor of the present invention, which discloses a dynamic patella brace that applies medial pressure to the patella throughout substantially the complete physiologic range of flexion and movement of the knee when the brace is in use. Even this patent, whose principles have been widely accepted over the years, suffers from the disadvantage that when the brace is in use, the patella bracing pad tends to be maintained in a relatively rigidly fixed position during flexion of the knee, and thus fails to effectively maintain pressure on the patella during flexion. This rigidity in the positioning of the pad results in lowered efficacy of the brace, because the pad is not permitted to dynamically reposition itself with respect to the sleeve or to float with respect to the patella during flexion of the knee, and thus the pad does not remain as effectively positioned as when the brace was initially engaged.